138 EFFECTS OF HEAT. 



A. 1st They act as screens to 

 arrest the radiation of heat from the 

 earth : 



2ndly They temper the heat of the 

 suns rays: and 



3rdly They are the great store-houses 

 of rain. 



Q. Why is WIND said to BLOW UP the 

 CLOUDS ? 



A. When a dry wind travels over 

 sea, and accumulates more vapour than 

 the air can sustain, it relinquishes a part 

 (as it flies along) in the form of clouds. 



Q. Why does WIND sometimes DRIVE AWAY 

 the CLOUDS ? 



A. When wind travels over dry 

 climes or thirsty deserts, it becomes so 

 dry itself, that it absorbs vapour from 

 the clouds, and disperses them. 



Q. What is the CAUSE of a RED SUN-SET ? 



A. Because the vapour of the air 

 is not actually condensed into clouds, 

 but only on the point of being condensed; 

 in which state it bends the red rays of 

 the sun towards the horizon, where they 

 are reflected at sun-set. 





